aren't they physically and mentally ready to play with kids the same age? why don't you simply call the school, ask for the A.D. and ask the question?
If they are physically and mentally ready to play at the Varsity level as a freshman, they would be physically and mentally ready to play with freshmen and sophomores on the JV, I think that goes without saying, but thank you Mr. Obvious. Don't need to call the A.D., just figured with the wealth of knowledge and expertise on this site, someone would answer other than "they have always done it that way" Maintaining the status quo is what shaped America
